The present invention relates generally to integrated circuit packages. More specifically, the invention relates to the singulation of integrated circuit packages.
An integrated circuit (IC) package encapsulates an IC chip (die) in a protective casing and may also provide power and signal distribution between the IC chip and an external printed circuit board (PCB). An IC package may use a metal lead frame to provide electrical paths for that distribution.
To facilitate discussion, FIG. 1 is a top view of a top view of a lead frame panel 100 made up for a plurality of lead frames that may be used in the prior art. The lead frame may comprise leads 108, die attach pads 112, ties 116 for supporting the die attach pads 112, and a skirt 120 for supporting the plurality of leads 108 and ties 116. The lead frame panel 100 may be etched or stamped from a thin sheet of metal. IC chips 124 may be mounted to the die attach pads 112 by an adhesive epoxy. Wire bonds 128, typically of fine gold wire, may then be added to electrically connect the IC chips 124 to the leads 108. Each IC chip 124 may then be encapsulated with part of the leads 108 and the die attach pad 112 in a protective casing, which may be produced by installing a preformed composite, plastic or ceramic housing around each IC chip or by dispensing and molding a layer of encapsulation material (mold compound), such as a composite or plastic material, over all IC chips 124. FIG. 2 is a cross-sectional view of part of the lead frame panel 100 and IC chips 124 that has been encapsulated by an encapsulation material 140, such as composite or plastic. The encapsulated IC chips are singulated. Dashed line 132 indicates a singulation line. FIG. 3 is a bottom view of a single singulated encapsulated IC chip 300. The encapsulation material 140, die attach pad 112 and leads 108 are shown.
Since during the singulation process, the cutting of encapsuration material, metal leads, and silicon is achieved, the method of singulation is very critical. If a sawing method is used for singulation, the metal in the lead or frame may smear or burr due to heat generated by the sawing process. Other methods of singulation may be by laser or water jet, which may also generate heat and cause unwanted damage. Such singulation methods may cause the metal leads to smear, caused by melting, or burr, which may cause shorting between the leads. Solder or lead may also melt disrupting electrical connections. In FIG. 3, shorting 304 between the leads is shown.
It is desirable to provide an IC package singulation process, which reduces damage to the encapsulated IC packages, such as shorting, metal lead smear, melting, or burring.
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, a variety of techniques is provided for making packaged chips. Generally, a panel is placed in a singulating device. Fluid is placed in a chiller system. The fluid is cooled in the chiller system. The cooled fluid is provided to an area of the panel to be singulated. The panel is then singulated.
Another aspect of the invention provides an apparatus for singulating a panel of encapsulated dice. A singulating device for cutting the panel is provided. A chiller system for cooling a fluid is provided to the singulating device. A dispenser for directing the cooled fluid to an area of the panel being singulated is provided to the chiller system.
These and other features of the present invention will be described in more detail below in the detailed description of the invention and in conjunction with the following figures.